全文获取类型
收费全文 | 1485篇 |
免费 | 73篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 19篇 |
综合类 | 6篇 |
化学工业 | 272篇 |
金属工艺 | 26篇 |
机械仪表 | 20篇 |
建筑科学 | 104篇 |
矿业工程 | 1篇 |
能源动力 | 76篇 |
轻工业 | 223篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 69篇 |
一般工业技术 | 207篇 |
冶金工业 | 250篇 |
原子能技术 | 12篇 |
自动化技术 | 264篇 |
出版年
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 24篇 |
2020年 | 21篇 |
2019年 | 28篇 |
2018年 | 40篇 |
2017年 | 39篇 |
2016年 | 36篇 |
2015年 | 28篇 |
2014年 | 47篇 |
2013年 | 93篇 |
2012年 | 79篇 |
2011年 | 91篇 |
2010年 | 68篇 |
2009年 | 71篇 |
2008年 | 91篇 |
2007年 | 101篇 |
2006年 | 79篇 |
2005年 | 56篇 |
2004年 | 55篇 |
2003年 | 48篇 |
2002年 | 41篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 22篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 18篇 |
1995年 | 16篇 |
1994年 | 26篇 |
1993年 | 21篇 |
1992年 | 23篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 21篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 4篇 |
排序方式: 共有1565条查询结果,搜索用时 15 毫秒
51.
Fault diagnosis is very important for modern production technology and has received increasing theoretical and practical attention during the last few years. This paper presents a model-based diagnostic method for industrial systems. An online, real-time, deep knowledge based fault detection system has been developed by combining different development environments and tools. The system diagnoses, predicts and compensates faults by coupling symbolic and numerical data in a new environment suitable for the interaction of different sources of knowledge and has been successfully implemented and tested on a real hydraulic system. 相似文献
52.
O. Kolditz S. Bauer N. Böttcher D. Elsworth U.-J. Görke C.-I. McDermott C.-H. Park A.K. Singh J. Taron W. Wang 《Mathematics and computers in simulation》2012
In this paper, conceptual modeling as well as numerical simulation of two-phase flow in deep, deformable geological formations induced by CO2 injection are presented. The conceptual approach is based on balance equations for mass, momentum and energy completed by appropriate constitutive relations for the fluid phases as well as the solid matrix. Within the context of the primary effects under consideration, the fluid motion will be expressed by the extended Darcy's law for two phase flow. Additionally, constraint conditions for the partial saturations and the pressure fractions of carbon dioxide and brine are defined. To characterize the stress state in the solid matrix, the effective stress principle is applied. Furthermore, the interaction of fluid and solid phases is illustrated by constitutive models for capillary pressure, porosity and permeability as functions of saturation. Based on this conceptual model, a coupled system of nonlinear differential equations for two-phase flow in a deformable porous matrix (H2M model) is formulated. As the displacement vector acts as primary variable for the solid matrix, multiphase flow is simulated using both pressure/pressure or pressure/saturation formulations. An object-oriented finite element method is used to solve the multi-field problem numerically. The capabilities of the model and the numerical tools to treat complex processes during CO2 sequestration are demonstrated on three benchmark examples: (1) a 1-D case to investigate the influence of variable fluid properties, (2) 2-D vertical axi-symmetric cross-section to study the interaction between hydraulic and deformation processes, and (3) 3-D to test the stability and computational costs of the H2M model for real applications. 相似文献
53.
Geoffrey Levine Ugur Kuter Antons Rebguns Derek Green Diana Spears 《Computational Intelligence》2012,28(3):329-357
We present a Bayesian approach to learning flexible safety constraints and subsequently verifying whether plans satisfy these constraints. Our approach, called the Safety Constraint Learner/Checker (SCLC), infers safety constraints from a single expert demonstration trace and minimal background knowledge, and applies these constraints to the solutions proposed by multiple planning agents in an integrated and heterogeneous ensemble. The SCLC calculates how much to blame plan fragments (partial solutions) generated by the individual planning agents. This information is used when composing these fragments into a final overall plan. In particular, fragments whose safety violations exceed a threshold are rejected. This facilitates the generation of safe plans. We have integrated the SCLC within the Generalized Integrated Learning Architecture, which was designed for Defense Advanced Research Projects Agency (DARPA)’s Integrated Learning (IL) program. The main goal of the IL program is to promote the development and success of sophisticated systems that learn to solve challenging real‐world problems based on a simple demonstration by a human expert and exiguous domain knowledge. We present experimental results showing the advantages of the SCLC on two multiagent problem‐solving tasks that were benchmark applications in DARPA’s IL program. 相似文献
54.
Jan Novák Derek Nowrouzezahrai Carsten Dachsbacher Wojciech Jarosz 《Computer Graphics Forum》2012,31(4):1407-1413
A recent technique that forms virtual ray lights (VRLs) from path segments in media, reduces the artifacts common to VPL approaches in participating media, however, distracting singularities still remain. We present Virtual Beam Lights (VBLs), a progressive many‐lights algorithm for rendering complex indirect transport paths in, from, and to media. VBLs are efficient and can handle heterogeneous media, anisotropic scattering, and moderately glossy surfaces, while provably converging to ground truth. We inflate ray lights into beam lights with finite thicknesses to eliminate the remaining singularities. Furthermore, we devise several practical schemes for importance sampling the various transport contributions between camera rays, light rays, and surface points. VBLs produce artifact‐free images faster than VRLs, especially when glossy surfaces and/or anisotropic phase functions are present. Lastly, we employ a progressive thickness reduction scheme for VBLs in order to render results that converge to ground truth. 相似文献
55.
Deposition of tantalum films for protective coatings on steel has been investigated. The desired tough and ductile bcc phase of tantalum, rather than the normally deposited hard and brittle tetragonal phase, has been grown by DC magnetron sputtering on unheated substrates first covered with thin layers of tantalum nitride. The nitride was formed by reactive sputtering with nitrogen gas, with the same DC magnetron source and target as used for deposition of tantalum. The crystal structure and composition of the nitride promoting the growth of bcc Ta, previously undefined, has been identified as the metastable fcc (NaCl like) TaN. Alignment of the (111) crystallographic planes of fcc TaN with (110) planes of bcc Ta is discussed as a possible mechanism for this effect. The minimum thickness of TaN underlayer on steel, required to promote the growth of bcc Ta, has been established and found to be dependent on the substrate surface preparation. Scratch tests with a diamond tip showed that the nitride underlayer does not compromise the film adhesion. Stable and well-adhering coatings of bcc Ta with thickness ranging from tens of nanometers to tens of micrometers on steel with a thin TaN underlayer were obtained. The process of deposition of bcc Ta films, including the formation of TaN underlayers is described in detail. 相似文献
56.
In real-world environments it is usually difficult to specify the quality of a preventive maintenance (PM) action precisely. This uncertainty makes it problematic to optimise maintenance policy. This problem is tackled in this paper by assuming that the quality of a PM action is a random variable following a probability distribution. Two frequently studied PM models, a failure rate PM model and an age reduction PM model, are investigated. The optimal PM policies are presented and optimised. Numerical examples are also given. 相似文献
57.
Hisashi Abe Isao Yoshida Hiroki Hamada Derek Luke Yongbao Xin Yue Xu Rong Yang Eiric Johnstone Joe Acchione Paul Balmforth 《Journal of the Society for Information Display》2004,12(3):275-280
Abstract— Defect‐free large‐area inorganic thick‐dielectric EL (TDEL) displays using Color by Blue (CBB) technology have been successfully developed. We have achieved the world's highest blue‐phosphor luminance of 900 cd/m2 for a single‐pixel device by using CBB and by optimizing the e‐beam gun configuration and the flow rate of H2S in the vacuum chamber. By analyzing the defects on panels with triple‐pattern phosphors and CBB panels, we also found that the number of defects on CBB panels can be drastically reduced compared with those on triple‐pattern panels. The defect‐free 17‐in. VGA CBB panels show better characteristics, a high peak luminance of 600 cd/m2 and a high contrast ratio of 1000:1, compared with those of triple‐pattern panels. 相似文献
58.
A thermally compensated temperature sensor capable of highly accurate determination of surface temperatures has been demonstrated. The probe consists of a single crystal Y(3)Al(5)O(12) fiber terminating in a laser-heated Yb(3)Al(5)O(12) phosphor. It has been shown to have a measurement accuracy of approximately 1 degrees C. In principle, this device should work in the proximity as well as the contact mode. 相似文献
59.
Derek Partridge 《Digital Creativity》2013,24(3-4):155-160
Abstract The notion of ‘specification’ is generally held to be crucial to the process of software production and the anchor point for the science of computing. It has, however, no simple, well-defined meaning. There are a variety of interpretations and usages of the term. This paper surveys the field of possibilities, both to display this varietal profusion, and to make the point that no one interpretation has a sound claim to be the best. 相似文献
60.
Abstract THE DAGUERREOTYPE. — The first experiments made in this country with the instrument and process of M. Daguerre were exhibited yersterday [sic] by M. St. Croix, who has just arrived from Paris, in the presence of a select number of scientific men and artists … The place of exhibition was No.7, Piccadilly, nearly opposite the southern crescent of Regent-street, and the picture produced was a beautiful miniature representation of the houses, pathway, sky, &;c, resembling a beautiful mezzo tint. The experiments were perfectly satisfactory.1 相似文献